With highly integrated semiconductor devices in demand over recent years, developing minute patterns required for manufacturing semiconductor devices has become important. For example, a self-alignment double patterning (SADP) process has been developed for forming a minute pattern having a high resolution.
According to the SADP process, a first mask pattern is formed on a substrate and then a sacrificial layer is successively formed on the first mask pattern. A hard mask layer is formed on the sacrificial layer and then the hard mask layer is partially etched to form a second mask pattern, to thereby form a mask structure including the first and the second mask patterns on the substrate.
As a result, not a single mask pattern but a double mask pattern including the first and the second mask patterns is formed by the SADP process. Using the double mask pattern when manufacturing a semiconductor device, a minute pattern may be obtained for the semiconductor device.
However, according to a conventional SADP process, using the first and the second mask patterns, the hard mask layer may not be sufficiently removed from the substrate so that residues of the hard mask layer may remain on the substrate in a process for forming the second mask pattern by removing the hard mask layer. Particularly, if the first mask pattern has a corner structure including a corner portion, an etched amount of the hard mask layer adjacent to the corner portion may be different from an etched amount of the hard mask layer which is formed over the first mask pattern, thereby leaving residues near an inner side wall of a corner portion, so that the mask structure may not be precisely formed on the substrate.
Hence, the conventional SADP process may undesirably leave residues from the hard mask layer on a substrate, thereby preventing formation of a minute pattern on the substrate.